Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02372008 2001-10-29
SPECIFICATION
Cultivation method for Erimo-shozu and harvest and storage methods for the
seed thereof
Field of the Invention
The present invention relates to a method for cultivating Erimo-shozu and a
method for
harvesting and storing the seeds thereof. These methods allow the production
of high-
' quality seeds of Erimo-shozu even in a low latitude district. Seeds of Erimo-
shozu
cultivated, harvested and stored according to the present invention possess
high-quality
equivalent to those cultivated in a high latitude district such as Hokkaido,
though the high-
quality seeds could have been obtained only in a high latitude area.
Background of the Invention
Adzuki beans are leguminous annual herb crops. They are generally red or
reddish brown,
and some of the varieties are brown or white. The varieties include Erimo,
Sahoro, Hayate,
Kotobuki, Akenowase, Hatsune and the like. Adzuki beans are consumed mainly as
bean-paste, ingredients for confectionary, in a large quantity in Japan. The
cultivation area
is limited since their quality and yields are largely affected by weather
conditions such as the
amount of solar radiation and of precipitation. In Japan 80% or more of the
gross domestic
yield of Adzuki beans are cultivated in Hokkaido where weather conditions
required for
Adzuki beans e.g., the amount of solar radiation or of precipitation are
satisfied.
To meet the demand of developing a variety suitable for cultivation in a
relatively cold
district, such as Hokkaido, Erimo-shozu (Adzuki Norin 4-go) has been bred from
Adzuki
plant that is generally sensitive to cold weather. Adzuki beans determined as
the one with
high quality possess characteristic features, such as good color, thin seed
coats, and a reduced
incidence of undesirable seeds called "hard beans" or immature seeds, those of
which cannot
be cooked in tender. In addition to have such features superior to other
varieties, Erimo-
shozu possesses additional features of strong resistance to cool weather, and
improved yields.
Continuous effort to breed Adzuki beans over the past 15 years has failed to
establish such a
variety having features superior to Erimo-shozu.
Breeding of a variety having qualities superior to Erimo-shozu would still be
difficult
because of long time period required for establishment of a new variety and of
the shortage of
manpower for breeding. Now the Erimo-shozu is a standard variety in the art.
Thus, a demand for Erimo-shozu is high among Adzuki beans. Now its gross yield
accounts
for 83% (% planted area) of Adzuki beans cultivated in Hokkaido. Although such
a high
1
CA 02372008 2001-10-29
demand for Erimo-shozu exists, the cultivation district is limited to Hokkaido
and almost no
Erimo-shozu is cultivated in other prefectures in Japan. This is because the
cultivation of
Erimo-shozu in prefectures other than Hokkaido results in harvest of reddish
black seeds,
which lose their original color tone. There is a report that experimental
cultivation of
Erimo-show in Ni-gata prefecture has caused the harvest of blackish seeds,
whose color is
different from the original color. Such seed color impairs its commercial
importance,
particularly reduces the worth of the Adzuki bean used for bean-paste.
Adzuki beans are also produced in countries other than Japan, for example in
China, Taiwan,
Canada, the United States of America, and Australia. In Japan domestic demand
of Adzuki
outpaces the supply. This shortage is covered by importing of Adzuki beans
from these
countries. However, Adzuki beans imported are different varieties and have
different taste
compared to those produced in Japan, and darker than Erimo-show. Thus the
imported
Adzuki beans are differentiated from the domestic Adzuki beans.
Since good-quality Erimo-shozu is produced only in Hokkaido, a poor crop
situation of
Erimo-shozu in Hokkaido causes problems including a sudden rise in prices due
to the short
supply. Therefore, stable supply of good-quality Erimo-shozu is required.
Problems to be solved by the Invention
The inventors conducted experimental cultivation of Erimo-shozu in Thailand
and the
produced seeds were blackish red, similar to those produced in the prefectures
other than
Hokkaido. In addition, many hard beans were found among the beans harvested.
If the cultivation of Erimo-shozu in a lower latitude area, differing from a
higher latitude area
in the weather conditions, becomes possible, stable supply of Erimo-shozu can
be realized.
The benefits from such a breakthrough would be immesurable. The present
invention has
been achieved against such technical background. The purpose of the invention
is to
provide means to produce good-quality Erimo-shozu even in a lower latitude
area and to
realize stable supply of such Erimo-shozu.
Means to solve the Problems
As a result of diligent investigation to solve the above described problems,
the inventors have
found that the average minimum temperature and the average maximum temperature
in a
certain period before harvest are closely related to the color tone of the
seeds and that the
water content of the seed is closely related to the incidence of hard beans.
Based on these
findings, the inventors have completed the present invention.
2
CA 02372008 2001-10-29
The first invention is a method for cultivating Erimo-show in an area between
25~ north
latitude and 25~ south latitude, characterized in that the seeds are
cultivated under the
condition wherein the average minimum temperature for 30 days before harvest
is 18.5'C or
less, and the average maximum temperature is 29.0'C or less.
The second invention is a method for harvesting seeds from Erimo-shozu
cultivated
according to the above described method, characterized in that the seeds are
harvested at a
time period when the water content of the seed in the pod localized lowest
among the pods
are 10% or more.
The third invention is a method for storing the seeds of Erimo-shozu,
characterized in that the
water content of the seeds of Erimo-show is kept at 10% or more during storage
by
preventing the decrease in the water content.
Brief Description of Drawing.
Figure 1 shows the water content for hard beans and normal beans.
Description of the Invention
Detailed description of the present invention will be given below.
( 1 ) Method for cultivating Erimo-shozu
A method for cultivating Erimo-shozu according to the present invention is
characterized in
that the seeds are cultivated under the condition wherein the average minimum
temperature
for 30 days before harvest is 18.5'C or less and the average maximum
temperature for the
same is 29.0'C or less.
Any cultivation area between 25' north latitude and 25' south latitude can be
included.
Preferable areas are situated between the tropic of Cancer (23.27' north
latitude) and the
tropic of Capricorn (23.27' south latitude). More preferable areas are
situated between
17' and 21~ north latitude, or between 17~ and 21~ south latitude.
A certain temperature is required for cultivation only for 30 days before
harvest.
Temperatures for periods other than those specified can be optionally set
within a range that
does not adversely affect the growth of the plant. That is, the average
minimum temperature
for 30 days before harvest may be at 18.5'C or less and the average maximum
temperature
3
CA 02372008 2001-10-29
for the same may be at 29.0'C or less. Preferably for cultivation, the average
minimum
temperature is at 17.0'C or less and the average maximum temperature is at
28.O~C or less.
More preferably, the average minimum temperature is at 16.0'C or less and the
average
maximum temperature is at 26.5'C or less. The lowest limit for the average
minimum
temperature or for the average maximum temperature can be optionally set
within a range
that does not adversely affect the growth of the plant.
Methods for keeping such temperature condition in a low latitude area can
include a method
for cultivating the seeds in alpine regions where the temperature is lower
than that in flatland
and a method for cultivating indoors where the temperature is controlled.
Seeds produced by these methods are light in color, which is the original
color tone of Erimo-
shozu. That is, the L* value for the seed color is 22 or more, b* value 11 or
more,
preferably the L* value is 23 or more, and b* value is 12 or more, more
preferably, the L*
value 24 or more, and the b* value 13 or more. In the present invention L*
values and b*
values are measured by a colorimeter or a color-difference meter based on
L*a*b*color
system. The L* value indicates lightness and b* value yellowness. A preferable
colorimeter or a color-difference meter is CR-300 (manufactured by Minolta
Co.,Ltd) or its
compatible. Each of L* values and b* values is obtained by mixing seeds
produced from
the entire field, extracting samples, measuring the color tone using the
colorimeter, and
calculating the average.
(2) Method for harvesting Erimo-shozu seeds
A method for cultivating Erimo-shozu seeds according to the present invention
is
characterized in that the seeds are harvested when the water content of the
seed in the
lowermost pod of a plant is 10% or more. The harvest time is, but not limited
to, the time
when the water content of the seed in the lowermost pod of a plant is 10% or
more. Too
early harvesting can lead to immature seeds in pods localized on the upper
portion.
Therefore, harvest is preferably done at a time period when the water content
of the seed in
the lowermost pod of a plant is 10% or more and the seeds appropriately mature
in the pods
localized on the upper portion.
The incidence of hard beans can be lowered by harvesting the seeds according
to the method.
(3) Method for storing Erimo-shozu seed
A method for storing Erimo-shozu seeds according to the present invention is
characterized
in that the water content of the seed of Erimo-shozu is kept at 10% or more
during storage by
4
CA 02372008 2001-10-29
preventing the decrease in the water content.
Any Adzuki beans can be stored, however, the Adzuki beans cultivated or
harvested by the
above described methods can be stored more effectively.
The water content of the seed is kept at 10% or more, or preferably at 11 % or
more, and more
preferably at 12% or more.
Means to prevent the decrease in the water content of the seed can include,
but not limited to,
a method wherein the seeds are stored indoors or containers which are kept at
constant
humidity, or a method wherein the seeds are stored in an airtight container or
a sealed bag.
The occurrence of hard beans can be inhibited by storing seeds after harvest
in this manner.
Examples
Example 1
Correlation between cultivation district and color tone
Method: Erimo-shozu seeds were sown in 11 locations (A to K districts) in
Thailand from
the middle to the end of August and were harvested from the end of October to
the middle of
November. Part of the seeds harvested is picked out for sampling (seeds that
exhibited
peculiar color or peculiar shape were excluded) and the color tone was
measured using a
colorimeter CR-300 manufactured by Minolta Co., Ltd.
Results: Tables 1 and 2 show the height above sea level, latitude, measured
color tone,
average maximum temperature and average minimum temperature for 30 days before
harvest
for each cultivating district. A correlation between L* value and average
maximum
temperature and the one between L* value and average minimum temperature were
correlation coefficient of -0.76 and -0.97, respectively. A correlation
between b* value and
average maximum temperature and the one between b* value and average minimum
temperature were correlation coefficients of -0.88 and -0.78, respectively.
For all of them,
significant differences were seen at the ratio of risk of 1 % or less.
CA 02372008 2001-10-29
Table 1 Temperature and color tone for 30 days before harvest (in order of L*
value)
Location Height Latitude Color Average maximum Average minimum
tone temp. temp.
for above (North L* b* for 30 days beforefor 30 days before
cultivationsea levellatitude) harvest harvest ( C)
('C)
A 1,400 20 27.714.3 22.2 10.4
B 1,000 18.6 25.213.0 26.5 15.0
C 680 19.6 23.911.4 27.4 15.9
D 1,360 19.2 23.111.9 22.4 16.4
E 470 19.5 22.39.9 28.9 18.3
F 1,280 18.5 22.211.2 26.5 18.3
G 1,300 18.5 22.010.8 29.5 18.1
H 520 20.2 21.311.0 31.0 19.8
I 800 19.3 20.911.2 28.0 20.9
J 440 20.4 20.79.1 30.6 18.4
K I 500 ~ 18.7 I 6.5 35.6 21.0
20.2
~
Correlation coefficient of L* value and the average maximum temperature: -0.76
Regression equation: y = -1.31x + 57.8
Correlation coefficient of L* value and the average minimum temperature: -0.97
Regression equation: y = -1.32x + 47.4
Table 2 Temperature and color tone for 30 days before harvest (in order of b*
value)
LocationHeight Latitude Color Average maximum Average minimum
for above (North tone temp. for temp. for
cultivationsea levellatitude) L* 30 days before 30 days before
b* harvest (C) harvest (C)
A 1,400 20.0 27.714.3 22.2 10.4
B 1,000 18.6 25.213.0 26.5 15.0
D 1,360 19.2 23.111.9 22.4 16.4
C 680 19.6 23.911.4 27.4 15.9
F 1,280 18.5 22.211.2 26.5 18.3
I 800 19.3 20.911.2 28.0 20.9
H 520 20.2 21.311.0 31.0 19.8
G 1,300 18.5 22.010.8 29.5 18.1
E 470 19.5 22.39.9 28.9 18.3
J 440 20.4 20.79.1 30.6 18.4
- - -
K I ~ 18.7 20.26.5 35.6 21.0
500 1
Correlation coefficient of b* value and the average maximum temperature: -0.88
Regression equation: y = -1.66x + 46.2
Correlation coefficient of b* value and the average minimum temperature : -
0.78
Regression equation: y = -1.16x + 30.2
6
CA 02372008 2001-10-29
Example 2
Relation between water content and incidence of hard beans
Water absorption test for Adzuki beans
Method: (1) Each of sixty Erimo-shozu beans harvested in Thailand and having
normal
appearance were weighed accurately (Adzuki bean weight:a). (2) One Adzuki bean
each
was added together with about 1 ml of ion exchange water into a tube and
allowed to stand for
24 hours at room temperature. (3) Each Adzuki bean was then removed, the
surface was
wiped to remove water, and then the bean was weighed accurately (Adzuki bean
weight after
absorption:b). (4) After absorption, the Adzuki beans were dried under normal
pressure at
IOS~C for 20 hours. Then the water content of the beans after the absorption
were measured
based on the weight loss on drying (water content of Adzuki bean after
absorption:c). (5)
Based on the above results, the water content (d) and moisture percentage (e)
for the original
Adzuki bean was obtained by the following equation.
d=a-(b-c) e=d/ax 100
Results: Table 3 and Figure 1 show results totaled separately for Adzuki beans
that absorbed
(normal bean) and for beans that absorbed no water (hard bean). As clearly
shown in Table
3 and Figure 1 there is a large difference in water content between the normal
beans and the
hard beans. The water content for the hard beans were far lower than that of
the normal
beans as expected.
Table 3
Number of Weight Water content
beans (g) (%)
~~
Normal beans19 0.120.0213.550.90
Hard beans 41 0.13 9.52 0.42
0.02
The results of water absorption test for Adzuki beans clearly indicated that
the formation of
hard beans depend on the water content of the Adzuki bean after harvest. It
was confirmed
that the formation of hard beans can be inhibited by keeping the water content
of the Adzuki
beans at 10% or more during storage. Further, the formation of hard beans can
also be
inhibited by harvesting the beans at the time period when the water content of
the bean in the
pod is 10% or more.
7
CA 02372008 2001-10-29
Effect of the Invention
According to the methods of the present invention, Adzuki beans with quality
equivalent to
Erimo-shozu produced in Hokkaido can be produced even in a low latitude area.
8
